THE FIRST ELECTRICAL MEASURING INSTRUMENT. 523 



life in beetles and worms ; but not succeding in so doing 

 in birds, sought still further to intensify the discharge, and 

 thus reached the idea of combining the effects of several 

 jars, which he placed in metal pans, with their lead balls 

 in contact with the prime conductor of his machine, while 

 from each pan a wire proceeded to a copper globe placed 

 within sparking distance of the conductor. This was the 

 first grouping of electric generators in battery, in which 

 they were obviously disposed in parallel, or multiple arc 

 an arrangement which for some time was the only one 

 known. 



Gralath now killed birds easily, and reports minutely on 

 the physiological changes produced ; but, as he saw that 

 whatever the effects of these strong discharges might be, 

 no certain knowledge as to them could be obtained unless 

 their strength could be measured, he turned his efforts to 

 contriving a measuring instrument. But he soon found 

 the difficulties insuperable. What should be the standard? 

 What the unit? What was really to be measured the at- 

 tractive power of the charge, or the striking energy of the 

 discharge ? He arranged near a scale-pan, which he main- 

 tained in a non-electrified state, an iron rod which com- 

 municated with his machine the rod being adjustable 

 nearer to or further from the scale-pan, and attracting the 

 latter when electrified. The attractive force of the rod 

 was counterbalanced by weights in the opposite pan. His 

 factors were the distance of the electric machine from the 

 apparatus, the distance of the rod from the scale-pan and 

 the balancing weights ; and he tabulates his results, arriv- 

 ing at the conclusion that with the rod distant half an inch 

 from the scale-pan, the ratio of attractive force, when the 

 electric machine was at maximum distance from the appa- 

 ratus, to that existing when the machine was at minimum 

 distance therefrom, was as 74 to 44 ; and that this inverted 

 represented the relative strengths of the corresponding dis- 

 charges. He had no faith in his deduction, which, he 

 says, requires proof by long trials and experiment, and 



